How to repair medial meniscal ramp lesions: A systematic review of surgical techniques

Abstract Purpose to provide a comprehensive overview of all the surgical techniques published in the literature for repairing meniscal ramp lesions focusing on the technical aspects and the pros and cons of every procedure. Such lesions can be managed using various approaches, each of this with its specific advantages and disadvantages. Methods Pubmed Central, Scopus, and EMBASE databases were systematically reviewed according to the preferred reporting items for systematic reviews and meta‐analysis (PRISMA) guidelines for studies on surgical techniques for repairing meniscal ramp lesions through May 2023. Overall, 32 articles matched the selection criteria and were included in the study. Results Debridement alone may be sufficient for small stable meniscal ramp lesions but, for tears in the menisco‐capsular junction that affect the stability of the medial meniscus, it seems reasonable to repair it, even though the clinical results available in literature are contrasting. All‐inside sutures through anterior portals seems to be an effective solution for meniscal ramp lesions with MTL tears. All‐inside sutures through posteromedial portals are particularly useful for large meniscal ramp lesions, in which an inside‐out suture can also be performed. Conclusion Meniscal ramp lesions can be managed using various approaches, each of this with its specific advantages and disadvantages. Further research is required to determine the optimal technique that can be considered as the gold standard and can provide the better results. Level of Evidence Level III, systematic review.


INTRODUCTION
Meniscal ramp lesions have gained a renewed interest due to its high correlation with anterior cruciate ligament (ACL) tears, up to 42% [7,34,40], and when this occurs there is an even greater increase of the anterior tibial translations and rotational laxity, and it has been shown that such biomechanical modifications could drive to increased cartilage degeneration if left unrepaired [19].A classification system has been proposed for meniscal ramp lesions, with five initial types based on tear location: type 1 involves meniscocapsular tears located peripherally in the synovial sheath; type 2 comprises partial superior lesions; type 3 corresponds to partial inferior lesions; type 4 involves complete tears in the red-red zone; and type 5 corresponds to double tears [42].This classification has been subsequently modified with the addition of two subtypes for type 3 and type 4 lesions: type 3A represents partial inferior lesions with an intact meniscotibial ligament (MTL), while type 3B represents partial inferior lesions with a MTL tear; type 4A involves complete tears in the red-red zone with an intact meniscocapsular attachment but connected to the freefloating fragment of the PHMM; and type 4B involves a complete tear where the meniscotibial and meniscocapsular fibers attach to the posterior horn medial meniscus (PHMM) [18].Due to the complex anatomy of this area a precise preoperative diagnosis is always tricky.Magnetic resonance imaging (MRI) has shown to have a specificity of 94% and a sensitivity up to 84% if a 3.0 Tesla MRI is used and the acquisition is performed with the knee at 30°of flexion [29].The MRI findings indicative of a ramp lesions are the irregularity at the posterior margin of medial meniscus and the interposition of synovial fluid between the PHMM and the capsule as the most sensitive findings [17,32,49], and recently, posteromedial tibial bone bruise has been identified as a possible diagnostic sign of these lesions [6,13,30].However, the pre-operative diagnosis of ramp lesions both coupling clinical and radiological findings is still far to be clear, and the systematic arthroscopic exploration of the posteromedial compartment remains mandatory not to overlook this injury [41].To avoid its detrimental effects a variety of treatment has been advocated, and even though "nontreatment" of stable ramp lesions has been proposed with good clinical results, surgical repair remains the main option [3,5,46].To date, there is no gold standard procedure for repairing these injuries and the surgeon should be aware of the different surgical options to apply them in the most appropriate case.Therefore, the purpose of this study was to provide a comprehensive overview of all the surgical techniques published in the literature for repairing meniscal ramp lesions focusing on the technical aspects and the pros and cons of each procedure.

MATERIALS AND METHODS
A literature review was performed using a search strategy design to collect articles regarding surgical repair of meniscal ramp lesions.The inclusion criteria adopted were as follows: (1) studies with at least one surgical technique for repairing meniscal ramp lesions; (2) articles published within the last 20 years; (3) studies published in English; and (4) studies involving human species (including cadaveric studies).Review articles were excluded from the search.

Article selection
The search was conducted according to the preferred reporting items for systematic reviews and metaanalysis (PRISMA) Guidelines [36] by a reviewer on PubMed Central, Scopus, and EMBASE, for studies available until May 2023.The keywords used for initial screening were ((((meniscal Ramp injury) OR (meniscal ramp lesion)) OR (meniscal ramp)) OR (ramp lesion)) AND ((operative technique) OR (repair) OR (suture) OR (management)).
Two authors (Luis L. Urda and Nicola Pizza) independently reviewed each article's title and abstract from the literature research.The assessors were not blinded to the authors of the publications.The full text was obtained and evaluated when eligibility criteria could not be assessed from the initial screening.
Finally, a summary of pearls, pitfalls, advantages, and disadvantages of each technique reported can be found in Table 2.

DISCUSSION
The objective of the present study was to review the surgical techniques reported in the literature for the repair of meniscal ramp lesions.Several techniques have been described for repairing these lesions, with the most frequently utilized method being all-inside sutures.The all-inside techniques can be further classified based on their approach, including anterior arthroscopic portals, a posteromedial portal, dual posteromedial portals, or a trans-septal portal suture repair technique.Additionally, inside-out techniques have been documented for repairing meniscal ramp lesions.
Ramp lesions managed without repair deserve a special mention.

Debridement or abrasion without repair
Ramp lesion with a length less than 2 cm or without excessive anterior translation of the PHMM upon probing from the anteromedial portal, are defined stable and can be managed with only a debridement.This involves placing the arthroscope through the transcondylar space and refreshing the two edges of the tear [48].Another technique involves abrasion and trephination of the torn meniscus through the posteromedial portal [35].
Hatayama et al. [22] conducted a study comparing the postoperative outcomes for ramp lesions between 25 patients treated with all-inside repair through the posteromedial portal and 25 patients whose ramp lesions were left in situ without repair during ACL reconstruction.The healing rate of ramp lesions showed a significant difference between the nonrepaired group and the repaired group (60% vs. 100%, p = 0.001).Moreover, two knees in the non-repaired group required medial meniscectomy for subsequent bucket-handle tear one and five years after ACL reconstruction, whereas no knees in the repaired group required subsequent meniscal surgery.
In contrast, Yang et al., [48] compared the efficacy of arthroscopic refreshing treatment of stable meniscus ramp injuries with the all-inside suture with FastFix device in cases of concomitant ACL tear.The authors reported similar clinical results in terms of the Lysholm, IKDC, knee range of motion, and recovery of objective symptoms.MRI findings at 12 months showed complete healing in 18 patients in the refreshing treatment group, as well as 21 patients in the repaired group, without significant difference.Furthermore, in a randomized controlled trial, Liu et al. [35] compared the

Sutures through anterior arthroscopic portals
Among the all-inside techniques, the repair of meniscal ramp lesions through anterior standard arthroscopic portals have been extensively discussed.Li et al. [33] introduced the Fast-Fix (Smith & Nephew) technique for repairing meniscal ramp injuries.Their recommended approach involved arthroscopic visualization of the posteromedial compartment by inserting the arthroscope through an anterolateral portal and advancing it through the intercondylar notch beneath the posterior cruciate ligament (PCL).The surgical procedure is performed introducing the Fast-Fix device through the anteromedial portal with the assistance of a split cannula to ensure its safe insertion.The ramp lesion is then fixed by inserting the first implant into the joint capsule beneath the meniscus and the second implant catching the periphery of the meniscus and the capsule (Figure 2).In some cases, visualizing PMHH can be challenging due to a narrow medial compartment.To address this, a medial collateral ligament (MCL) release using a pie-crusting technique has been employed to facilitate visualization and treatment of meniscal ramp lesions [11,26,31].This technique involves needling the superficial MCL with an 18-gauge needle while the knee is in a valgus position at 15-20°of flexion.The needle is inserted 1 cm distal and in the posterior third of the joint line (Figure 3).However, it is important to note that MCL release carries the risk of iatrogenic complete MCL rupture and mostly saphenous vein and nerve damage if performed too posteriorly.
One concern with all-inside suture through anterior portals is the re-tension that can be achieved on the MTL.Negrín et al. [38] suggested that elevating the MTL using an arthroscopic grasper inserted through a posteromedial portal (or an 18-gauge needle, as in authors experience) (Figure 4) and then deploying the all-inside suture the proper tension of the MTL can be 2. Additional risk of iatrogenic injury to saphenous structures.
achieved.However, this approach has the disadvantage of requiring an additional posteromedial portal, which carries a risk of neurovascular damage.Suturing meniscal ramp lesions through the AM portals offers several advantages, including an effective and safe technique that is less time-consuming and has a short learning curve.However, there are also disadvantages, such as higher costs due to the use of devices, decreased accuracy in determining the extent of the tear, and limited usefulness for MTL lesion.
The all-inside suture through anterior portals have shown promising clinical and functional outcomes in isolated meniscal ramp lesions [24,25], and with concomitant ACL reconstruction [10].Jiang et al. [24] evaluated 20 isolated meniscal ramp lesions showing its healing 3 months follow-up and a significant improvement of the Lysholm score at 2 years follow-up.Also, Karaca et al. [25] showed a significant improvement in the postoperative Lysholm and IKDC scores, meniscal healing and improvement of the anterior laxity evaluating 41 patients with type 3 meniscal ramp lesion (combination of partial inferior PHMM tear and MTL tear) at 3 years follow-up.These successful results have even been seen by Chen et al. [10] which confirmed the meniscal healing of 46 ramp suture associated with concomitant ACL reconstruction with a second arthroscopic look at 3 years follow-up.On the other side, Thaunat et al. investigating the risk factors for failures of ramp repair identified a more than five-fold risk of failure if the repair is performed with all-inside sutures through anterior arthroscopic portals compared to suture hook repair technique.This finding seems in accordance with, Gousopoulos et al., [16] who compared the secondary meniscectomy rates of suture hook repair through a posteromedial portal and all-inside repair through anterior portals at a mean follow-up of 8 years months which was of 19% for the first one and 30% for the second one.

Sutures through a posteromedial portal
The all-inside techniques using a posteromedial portal can be achieved with two different devices.Brito de Alencar Neto et al. [8] recommended the use of a knee scorpion suture passer through a posteromedial arthroscopic portal because it is an easier and faster technique compared to the suture hook passer devices.However, this technique has similar disadvantages to other all-inside techniques through a posteromedial portal.
On the other hand, the repair of meniscal ramp lesions using a hook suture passer device has been widely described.Sonnery-Cottet et al. [41] moreover, outlined a systematic surgical exploration in four steps to avoid missing meniscal ramp lesions.The arthroscopic exploration of the posteromedial aspect through a trans-notch visualization is performed and a posteromedial portal is created.Finally, the meniscal repair procedure is performed using a suture hook device.Thaunat et al. [42] recommend creating the posteromedial portal 1 cm posterior to the medial femorotibial joint line with transillumination guiding the portal location.The lesion is then evaluated and debrided.A left curved hook device is used for the right knee and vice versa.Typically, the suture hook passer is loaded with an No. 0 or 1 absorbable monofilament suture, although a nonabsorbable monofilament suture can be used [41,47].To protect the medial condyle from iatrogenic cartilage damages, the tibia is internally rotated.The tip of the suture hook first penetrates the meniscocapsular ligament and MTL, and then the PHMM.The free end of the suture is extracted and collected through the posteromedial portal using a grasper.A self-locking sliding knot is tied using a knot-pusher and then cut [4,21,42,47] (Figure 5).
The advantages of this technique include its low cost, improved debridement of the lesion and better visualization of the PHMM and the meniscal ramp lesion.However, there are some disadvantages, such as the need for an additional portal which increases the risk of saphenous nerve or venous injury, a significant learning curve in creating the posteromedial portal and placing and tying sutures, as well as an increased operative time.
In a case series study, Thaunat et al. [44] evaluated the results of all-inside suture repair with a suture hook device through a posteromedial portal on 132 meniscal ramp lesions associated with an ACL rupture at 2 years follow-up.If the IKDC score significantly improved from the pre-operative to the final follow-up, the authors reported a slightly lower Tegner score with an overall | 11 of 16     failure rate of 9%.Thus, concluding that arthroscopic meniscal repair of ramp lesions during ACL reconstruction with a suture hook device through a posteromedial portal provided a high rate of meniscus healing at the level of the tear and appeared to be safe and effective in this group of patients.As mentioned earlier, Hatayama et al., [22] compared the results between meniscal ramp lesion repair and non-repair with concomitant ACL rupture demonstrating a significantly better healing at MRI in the repair group.Additionally, anterior laxity in the knees with an unhealed ramp lesion was significantly higher.
When it comes to comparing this technique to the all-inside suture through anterior arthroscopic portals controversial results are presents in literature.As mentioned before, some authors reported a higher secondary meniscectomy rate when comparing allinside suture from AM portals with the suture hook technique [32,47].However, in a prospective cohort study at minimum 2 years follow-up, Choi et al., [12] did not report a significant difference in meniscal healing on MRI nor in laxity measurement with the Lachman test and KT-arthrometer, or in the functional evaluation with Lysholm and Tegner scores between the two groups.

Sutures through two posteromedial portals
Among the all-inside sutures through two posteromedial portals, Ahn et al. [2] introduced this technique.The posteromedial compartment is approached by passing the arthroscope from the anterolateral portal through the intercondylar notch.Afterwards, a standard posteromedial portal is created under direct arthroscopic visualization.The posterior compartment is examined with a probe and by switching the arthroscope to the posteromedial portal, the lesion is completely visualized.The second posteromedial portal is marked 1 cm superior to the previous standard posteromedial portal.The entry point is localized with an 18-gauge needle while viewing from inside.Then the second posteromedial portal is made, which is bigger than the standard.A cannula is inserted through this second portal.
A suture hook device is inserted through the standard posteromedial portal, and the suturing is performed similarly to the one-posteromedial approach mentioned above.
To facilitate the suture, a probe is introduced through the second posteromedial portal and holds the central fragment down to the tibial surface, aiding in the suturing.
Siboni et al. [39] and Toanen et al. [45] introduced a modification of this technique.The posteromedial working portal is performed 1 cm anterior to the site of the standard posteromedial portal, and the accessory posteromedial viewing portal is established 3-4 cm proximally and slightly anterior to the posteromedial working portal.Both are established under transillumination to visualize and avoid iatrogenic injuries.
Thus, this technique allows for a better visualization of the ramp lesion, with easier triangulation if an accessory posteromedial viewing portal is established.Additional advantages include a lower rate of cartilage damage by the suture hook due to probe assistance and the use of vertically oriented anatomic sutures.Disadvantages include the two additional posteromedial incisions with an increased risk of iatrogenic injury to saphenous structures and an increased operative time.
Gülenç et al. [20] conducted a prospective study to evaluated the results of surgical repair of 15 ramp lesions using this technique with a suture hook device with significant clinical improvement at 8 months follow-up.However, as we mentioned above, Liu et al. [35] compared the clinical outcomes of stable ramp lesions between patients treated with surgical all-inside suture through two posteromedial portals as described by Ahn et al., [2] or with abrasion and trephination alone during ACL reconstruction, reporting similar clinical outcomes in terms of subjective scores (Lysholm score and IKDC), knee stability (pivot-shift test, Lachman test, KT-1000 arthrometer SSD, and KT-1000 arthrometer grading), and meniscal healing status.

Sutures through a trans-septal portal technique
Ahn [1] described this technique to visualize and facilitate arthroscopic procedures in the posterior compartment both medial and lateral.Buyukdogan et al. [9] and Keyhani et al. [28] performed this technique for the repair of meniscal ramp lesions.A standard posteromedial portal is created under transillumination to avoid injury to the saphenous nerve or vein.To establish the posterolateral portal, the lateral collateral ligament, and long head of the biceps femoris must first be identified.Care must be taken to remain anterior to the long head of biceps femoris to minimize the risk of injury to the common peroneal nerve.This portal is also created under transillumination, followed by the insertion of a long arthroscopic cannula.
The following step is the aperture using a blunt instrument of the posterior septum to create the connection between the posteromedial and posterolateral compartments.The point of penetration in the septum should be just posterior to the PCL at the midpoint in a vertical position.If the aperture is too high, it may cause bleeding from the arterial branches of the middle geniculate artery, while if too low, there is a risk of injury to the popliteal vessels.Moreover, the aperture through the septum should be directed from posterior to anterior, again to avoid popliteal neurovascular damages while taking care of the PCL or the lateral femoral condyle cartilage.After having established the trans-septal aperture, the arthroscope can be switched to the posterolateral portal allowing a complete visualization of the meniscal ramp lesion.The suture is then performed using a suture hook device inserted through the posteromedial portal, as mentioned above.
Keyhani et al. [28] recommended a three-step augmentation procedure to achieve the best results in meniscal ramp repair.The first step involves thorough debridement of the fibrotic tissue at the posterior meniscosynovial junction.The second step involves using a meniscal rasp introduced through the posteromedial portal to abrasion both the synovial and meniscal sides of the tear.Finally, for in situ clot formation, an arthroscopic burr is introduced through the posteromedial portal to completely abrade the bony rim of the posteromedial tibial plateau until a bleeding subchondral cancellous bone is reached.
The trans-septal portal technique offers several advantages, such as the possibility to explore the entire periphery of the PHMM to define the exact borders of the ramp lesion without the need for a rotational manoeuvre as well as to place vertical mattress suture with the suture hook passers.
However, some disadvantages have been reported, such as the need to establish the posterolateral portal with the above-mentioned risks, a long learning curve, and an increased operative time.
Regarding the results of such technique, Keyhani et al. [27] analyzed a consecutive series of 128 cases performed in association with an ACL reconstruction.At a minimum follow-up of 2 years the Lysholm and the IKDC scores showed significant improvement with respect to the pre-op without any case of operativerelated complications.

Inside-out technique
The inside-out technique has been considered the gold standard for arthroscopic repair since its introduction in the 1980s.However, there is a lack of literature focused on the repair of meniscal ramp lesions using the insideout suture technique.DePhillipo et al. [14] described the inside-out repair of meniscal ramp lesions.Initially, the arthroscope is introduced through the anterolateral portal and advanced through the intercondylar notch to inspect the posteromedial compartment.Once a ramp lesion is identified, a medial approach is performed.An incision of approximately 4 cm in length is made posterior to MCL, two-thirds distal to the joint line and one-third proximal.The approach is carried out with the knee in flexion.The anterior sartorius fascia is identified and dissected, followed by retraction of the pes anserinus to protect the saphenous nerve.The medial gastrocnemius head is then dissected off the capsule using blunt dissection.Maintaining the knee in 70°-90°o f flexion helps to relax the hamstring and gastrocnemius, improving visualization and retrieval of the needle coming out from the joint for suture.The inside-out meniscal repair is performed by introducing an insideout device through the anterolateral portal.The first needle is passed through the meniscus, and the second needle is passed through the adjacent capsule to create a vertical or oblique suture.The knee is flexed to 10°-20°during needle advancement, and after the passage, the knee is flexed to 70°-90°to facilitate the needle retrieval.The knot is tied, and other stitches can be added as described.The main advantage offered by this technique is the possibility to change the suture fashion according to the lesion pattern.However, the need for an open approach carries an increased risk of iatrogenic injury to saphenous vessel and nerve.Nevertheless, in cases where a medial incision is performed for other reasons such as an MCL procedure, the inside-out technique can be taking into account (Figure 6).
When this technique is compared to the all-inside technique through a suture-hook device, Choi et al., [12] in a prospective cohort study detected an increased pivot-shift in patients with the inside-out suture but without differences in the Lachman test and KT-1000 arthrometer, nor differences in meniscal healing rate based on MRI.

Limitations
The present review has some limitations.First, the heterogeneity of the studies included which cannot give the possibility to drive solid conclusions on the clinical F I G U R E 6 Posteromedial incision for inside-out suture.
| 13 of 16     outcomes reported.However, it must be remembered that the main objective of the study was to revise all the available techniques presented in literature, without a specific focus on the clinical outcomes of such techniques which has been reported to give a comprehensive view on the described technique.Secondly the possibility of article selection bias which cannot be avoided a priori and may have affected the validity and generalizability of the present review.However, the authors strictly adhered to the PRISMA guidelines [36] and included both prospective and retrospective studies to provide the most comprehensive overview of this specific topic.
The relevance of the present study relies on the comprehensive revision of the surgical technique that have been described in the literature for the repair of meniscal ramp lesions of which the surgeon should be aware and should be part of its armamentarium to apply it to the most suitable situation.

CONCLUSION
Meniscal ramp lesions can be managed using various approaches, each of this with its specific advantages and disadvantages.Debridement alone may be sufficient for small stable meniscal ramp lesions but, for tears in the menisco-capsular junction that affect the stability of the medial meniscus, it seems reasonable to repair it, even though the clinical results available in literature are contrasting.All-inside sutures through anterior portals seems to be an effective solution for meniscal ramp lesions with MTL tears.All-inside sutures through posteromedial portals are particularly useful for large meniscal ramp lesions, in which an inside-out suture can also be performed.Further research is required to determine the optimal technique that can be considered as the gold standard and can provide the better results.

F
I G U R E 2 All-Inside suture through anterior arthroscopic portals.F I G U R E 3 Pie-crusting technique performed with an intramuscular needle.

F
I G U R E 4 (a) Elevating the meniscotibial ligament (MTL) with an 18-gauge needle introduced through the posteromedial compartment.(b) Good tensioning of the MTL can be observed.FI G U R E 5 All-Inside suture through a posteromedial portal using a hook suture passer device loaded with absorbable suture.
studies included in the review.Characteristics and results of the included studies.
Pearls, pitfalls, advantages, and disadvantages of the surgical techniques published in the literature.